TIM3 gene polymorphisms in patients with chronic hepatitis B virus infection: impact on disease susceptibility and hepatocellular carcinoma traits

Hepatitis B virus (HBV) infection is associated with the development of acute and chronic liver diseases including hepatocellular carcinoma (HCC). T-cell immunoglobulin domain and mucin domain-containing molecule-3 (Tim-3), which negatively regulates T-cell response and mediates phagocytosis of apoptotic cells, has been implicated in HBV infection and cancers. This study explored the polymorphisms of TIM3 gene in 535 patients with HBV-related liver diseases including 213 chronic hepatitis, 178 cirrhosis and 144 HCC, 72 HBV infection resolvers and 182 healthy controls and analyzed the effects of these polymorphisms on the disease susceptibility and HCC traits. TIM3-1541C/T, -1516G/T, -882C/T, -574G/T and +4259T/G polymorphisms were genotyped using polymerase chain reaction-restriction fragment length polymorphism. Of the five polymorphisms genotyped, the allele T-containing genotypes (GT + TT), allele T and allele T-containing haplotype (CTCGT) of -1516G/T polymorphism were more frequent in HBV patients than in controls [P = 0.005, odds ratio (OR) = 2.300, 95% confidence interval (CI): 1.294-4.088; P = 0.004, OR = 2.266, 95% CI: 1.297-3.962; and P = 0.005, OR = 2.203, 95% CI: 1.260-3.854, respectively]. The allele T-containing genotypes and allele T of -1516G/T were associated with HCC tumor grade (P = 0.023 and P = 0.017, respectively) and lymph node metastasis (P = 0.024 and P = 0.017, respectively). These findings suggest that -1516G/T polymorphism in the promoter region of TIM3 gene may affect the disease susceptibility and HCC traits associated with HBV infection, potentially supporting the role of Tim-3 in T-cell dysfunction and exhaustion involved in persistent HBV infection and HCC development.